There are various ways to evaluate languages; one that I think is interesting is to look at the influence the language in question has had and is having on other languages. Among older languages, Lisp and C are the clear leaders in this area, though there are others worthy of note (not that I'm going to bother at the moment). Among the current generation, though, I think Perl stands in pretty decent stead, though it may be too soon to really tell for sure.